Howard W. H. Lee, Gildardo R. Delgado, Boyd R. Taylor
Lawrence Livermore National Lab. (United States)
Peter A. Thielen, Susan M. Kauzlarich, Chung-Sung Yang
Univ. of California/Davis (United States)
Proc. SPIE 10299, Novel Materials and Crystal Growth Techniques for Nonlinear Optical Devices, 1029908 (June 21, 2017); doi:10.1117/12.419800
http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2634891
Inducing efficient visible light emission from silicon (Si) and understanding the underlying physics have long defined fascinating scientific and technological challenges. We present a comprehensive study on the origin and nature of red to ultraviolet (UV) light emission from Si quantum dots (QDs). We report the strongest quantum confinement (QC) effects to date and find that: (i) light emission can be stable in ambient and continuously tunable from the red to the UV through a single mechanism, i.e., QC, (ii) the energy gap increases from QC with decreasing size (Eg(d)- 1.14 ∝1/41.4) to energies significantly greater than previously observed (3.80 eV), (iii) the lowest optical transition remains predominantly indirect despite strong QC in small QDs (~14 Å diameter), and (iv) these properties can apply to QDs with and without a surface oxide layer. These results agree well with calculations that go beyond effective mass approximations. Visible light emission can also result from localized traps and may be mistaken for quantum confined emission.
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